Kaba Simplex 91904 Auxiliary Lock with Thumbturn; Deadlocking Spring Latch with Latch Holdback for 1Kaba Simplex 91904 Auxiliary Lock with Thumbturn; Deadlocking Spring Latch with Latch Holdback for 1 3 4" to 2 1 8" Door Satin Brass Finish Mechanical Pushbutton Lock Eliminates Problems and Costs Associated with Issuing, Controlling and Collecting Keys and Cards Provides Fully Mechanical Access Control at All Times While Allowing Free Egress At All Times By Interior Thumbturn Deadbolt Models Must Be Manually Relocked; Spring Latch Models